[BUG] ReactiveUI.XamForms, WhenActivated generates FileNotFoundException Could not load file or assembly 'ReactiveUI.Wpf' or one of its dependencies

[AkilaeTribe]

Describe the bug
In a Xamarin Forms projet, Using for the first time ReactiveUI.ViewForMixins.WhenActivated(this IActivatable @this, Action block, IViewFor view = null) generates two exceptions

System.IO.FileNotFoundException: Timeout exceeded getting exception details
System.IO.FileNotFoundException: Could not load file or assembly 'ReactiveUI.Wpf' or one of its dependencies

Steps To Reproduce

1. Create new Xamarin Forms project (the starting root page should not be relevant to the issue)
2. Install ReactiveUI.XamForms (problems seems present on 9.15.1 and 10.0.1-preview.3)
3. Declare a view model (no property or base class required)
4. Change base type of starting root page to matching ReactiveUI.XamForms one and using the view model type
5. Instantiate a view model inside the starting root page constructor, and assign it to BindingContext
6. Add in constructor this.WhenActivated(disposables => { });
7. Ensure FileNotFoundException type is checked, in the Exception Settings window
8. Run application for Android in Debug mode, using an emulator

Expected behavior
No exception happens.

Screenshots

Environment

• OS: Windows 8.1 Professional
• Version Android API 28 (emulator)
• Device: Pixel (emulator)
• IDE: Visual Studio 2019 Community 16.0.4

Additional context

Solution for reproduction
MonoReactiveUI.zip

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[glennawatson]

These won't crash your application correct? We just check for a series of approved DLLs. I don't believe this is a bug.

[AkilaeTribe]

These won't crash your application correct?

This is correct, the application does not crash.

We just check for a series of approved DLLs.

@glennawatson I apologize, I am unsure about the meaning of that sentence. Would you like to elaborate, please ? Are opened bug issues only handled if they are related to specific versions ? Or there is some hardcoded part that looks for specific versions of DLLs ?

I don't believe this is a bug.

If this is not a bug, then, do you agree that the exceptions are suspicious ? This is a Xamarin Forms project, with only one added NuGet package related to Xamarin Forms, yet the exception explicitly mentions Wpf. Even with a respectable 'Google-fu" skill, I was not able to find anything related to it, suggesting that I was doing something wrong.

[glennawatson]

No not suspicious.

ReactiveUI/src/ReactiveUI/Mixins/DependencyResolverMixins.cs

Line 34 in ddb56c7

"ReactiveUI.Wpf"

As I already said comes from our list of approved assemblies

[glennawatson]

Anyway locking this topic.

[glennawatson]

Btw don't feel too bad about the issue being locked. I am going to be locking most resolved issues from now on since we been having a lot of instances of people commenting on 4 year old bugs with new bugs.

[glennawatson]

So two changes that are happening as a response to this. We will be adding a section to the documentation just commenting on this side effect. Second initialisation is changing in rxui for V10 and this will eliminate these exceptions.

[RLittlesII]

Further progress for this can be tracked on #1737